Apparatus for stretch forming and punching metal stock and stock gripping head therefor



Jan. 5, 1965 s. M. DOLNEY 3,164,196

APPARATUS FOR STRETCH FORMING AND PUNCHING METAL STOCK AND STOCK GRIPPING HEAD THEREFOR 5 Sheets-Sheet 1 Filed May 18, 1961 INVENTOR. BY M fm'rae/v'x Jan. 5, 1965 s. M. DOLNEY 3,164,196

APPARATUS FOR STRETCH FORMING AND PUNCHING METAL STOCK AND STOCK GRIPPING HEAD THEREFOR Filed May 18. 1961 5 Sheets-Sheet 2 1N VEN TOR.

54 armwvax PUNCHING METAL STOCK D THEREFOR Jan. 5, 1965 s. M. DOLNE APPARATUS FOR STRETCH FORMING AND AND STOCK GRIPPING HEA Filed May 18, 1961 5 Sheets-Sheet 3 R 0 T. N

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Jan. 5, 1965 s. M. DOLNEY 3,164,196

APPARATUS FOR STRETCH FORMING AND PUNCI-IING METAL STOCK AND STOCK GRIPPING HEAD THEREFOR Filed May 18, 1961 23 1 1:12 of I \9 I I [E 1' l N w INVENTOR. WWW, BY

i Mme/var Jan. 5, 1965 s. M. DOLNEY 3,154,196

APPARATUS FOR STRETCH FQRMING AND PUNCHING METAL STOCK AND STOCK GRIPPING HEAD THEREFOR Filed May 18. 1961 5 Sheets-Sheet 5 INVENTOK I g ATTORNEY.

atet iiatented Jan. 5, 1965 fiice 3,164,196 APPARATUS FOR STRETQH FORMING AND PUNCHING METAL STOCK AND STDCK GRIIPING HEAD THEREFOR Stanley M. Dolney, Parma, Ohio, assignor to The Cyril Bath Company, Solon, Ohio, a corporation of Ohio Filed May 18, 1961, Ser. No. 110,931 1 Claim. (Cl. 15335) This invention relates to an apparatus for forming metal stock, and particularly to an apparatus for combined stretch forming and punch forming of the stock, to the stock gripping head, and to the adjustment means for the punch forming tooling.

For the purposes of illustration, the method and apparatus are described herein in connection with the stretch forming of elongated metal trim having a J-Shaped cross section of which the hook of the J and a portion of the leg are covered exteriorly with woven or preformed flexible sheet material or fabric. Their use in this connection well illustrates the general, and some specific, problems involved and the advantages of the present apparatus in connection with the solution thereof.

The invention is shown as embodied in a machine of the general character disclosed in US. application Serial No. 12,161, filed March 1, 1960, by Robert F. DeMarco and and now Pat. No. 3,025,904 and Serial No. 20,689, filed April 7, 1960, by Robert F. DeMarco and Pius J. Nasvytis and now Pat. No. 3,068,928.

A principal object of the invention is to'grip and release stock more effectively during tensioning of the stock.

Another object is to provide a stretch forming head having gripping jaws which hold the stock firmly during forming, but do not adhere to the stock when they are opened to release it from the head, whereby the stock can be removed readily therefrom.

Another object is to form the stock at desired locations along its length by punching or cutting the metal while it is held under stretch forming tension on the die face by the stretch forming apparatus.

A correlative object is to punch th metal in directions generally parallel to the die face while it is tensioned.

Additional objects are to position the stock effectively .for the pressing or punching operation when it is disposed in diderent positions on the die, and to arrange the jaws so they can be reversed and inverted from end to end of the stock to be formed so that the same jaws can readily be used for right and left matching articles.

Various other objects and advantages of the invention will become apparent from the following description in which reference is made to the drawings, in which:

FIG. 1 is a top plan view of a length of stock to be formed in accordance with the present invention;

FIGS. 2 and 3 are a bottom plan view and a right end view, respectively, of the length of stock illustrated in FIG. 1;

FIG. 4 is an enlarged. cross sectional view of the stock taken on the line 44 in FIG. 1;

FIG. 5 is a top plan view of an apparatus embodying the principles of the present invention;

FIG. 6 is a front elevation of the apparatus illustrated in FIG. 5;

FIG. 7 is a sectional view taken on the line 77 in FIG. 6;

FIG. 8 is a front elevation of the gripping head used in the present invention;

FIG. 9 is a vertical sectional view through the head, taken on the line 99 of FIG. 8, parts thereof being shown in section for clearness in illustration;

FIG. 10 is a front elevation, partly in section, of one of the metal punch forming tools used in the present apparatus.

FIG. 11 is a vertical cross sectional view of the tool, taken on the line 11-11 in FIG. 10, part thereof being shown in section for clearness in illustration;

FIG. 12 is a fragmentary front elevation of the apparatus illustrated in FIG. 11, showing the parts in a different position;

FIGS. 13 and 14 are diagrammatic illustrations illustrating different positionings of the workpiece during forming in the apparatus;

FIG. 15 is a diagrammatic illustration of the jaws for holding the workpiece when the hook of the J is upwardly, as in FIG. 13;

FIG. 16 is a diagrammatic cross sectional view taken on the line 1616 of FIG. 15;

FIG. 17 is an illustration similar to FIG. 15 of the jaws for holding the workpiece when the hook of the J is downwardly, as illustrated in FIG. 14; and

FIG. 18 is a cross sectional view taken on the line 1818 in FIG. 17.

A length of stock to be formed is illustrated in FIGS. 1 through 4. This stock is J-shaped in cross section and has a web W and a flange F. A suitable decorative coating D of fabric or other decorative material, preferably of woven material, is secured on the stock and extends around the flange and part way along [the web to a location indicated at E. This decorative coating usually is about ten thousandths of an inch thick. The web also is to be worked on by a punching tool. For example, it may be worked on by punches which punch holes such as indicated at H, or cut notches, such as indicated at L. These specific shapes form no part of the invention but are to illustrate some of the problems involved.

Referring to the drawings, the apparatus comprises a frame 1 supporting a die table 2 on which, in spaced relation to its upper face, a side face die 3 is supported with its forming faces forwardly of the frame by suitable blocks 4.

For stretch forming a length of stock about the die face, a swinging arm 5 is mounted on a suitable upright pedestal 6 on the frame 1 for swinging about the upright axis of the pedestal, generally in a plane parallel to the top of the table. If desired, the arm may be mounted on suitable trunnions 7 so as to rock about a horizontal axis, this arrangement being used in those instances in which all portions of the side face of the die are not at the same elevation.

For operating the arm 5, a rocker arm 8 is rigidly connected thereto for swinging therewith about the axis of the pedestal 6. The arm 8 is driven by a reversible piston and cylinder assemblage 19, comprising a cylinder 11 in which is reciprocable a piston 12 having a piston rod 13. The piston rod 13 and crank 8 are connected by a pivot 14 so that, upon operation of the assemblage 10, the arm 8 is swung about the axis of the pedestal, thereby swinging the arm 5.

Mounted on the arm 5 for movement endwise thereof radially of the axis of the pedestal 6 is a stretch forming assemblage 29. This assemblage comprises a carriage 21 which is mounted on the arm 5 for sliding movement end wise thereof on suitable slideways 22. The carriage 21 is provided with a depending cam roller 23 which is rotatable about an upright axis and which engages a cam 24 fixedly mounted on the frame 1. l

A suitable compression spring 25 is interposed between an abutment 26 on the carriage 21 and an abutment 27 on the arm 5, the spring being retained in operating position by a suitable rod 28. The spring 25 urges the carriage toward the axis of the pedestal 6 and thereby yieldably holds the cam roller 23 in operative engagement with a cam 24. By varying the face of the cam, different predetermined movements of the carriage can be obtained.

, Mounted on the carriage 21 is a stretch gripping head 29 for gripping the end of the length of stock to be formed for applying endwise tension thereto as the carriage advances and recedes relative to the axis of the pedestal 6. f A complementary head 39 is mounted on the frame at the other end of the die. Since the heads are the same in form and function, being merely a left and right, only the head 30 will be described in detail.

The details of the gripping head 3%, of which the jaws are an important feature of the invention, are best illustrated in FIGS. 8 and 9. As there illustrated, the head 30 comprises a lower heel block 31 and an upper heel block 32 to which are fixedly connected a lower jaw block 33 and an upper wedge block 34, respectively. The blocks are connected together by suitable side plates 35 and 36 to define a housing for accommodating stock gripping aws.

The wedge block 34 has on its under surface a wedge surface 37. A sliding gripping jaw 38 is provided and has a complementary wedge surface 3 on its upper surface adapted for sliding engagement with the surface 37. The jaw 38 has a stock gripping surface 40 and, for use with stock of J-section, has at one side a suitable notch 41 to receive the hook of the J, as will later be described.

The jaw 38 is movable endwise along the surface 37 toward and away from the open front or stock insertion end of the gripping head, or the left edge of the head as illustrated in FIG. 9.

tween faces 40 and 56 of the two jaws and the jaw 38 is moved to the left in FIG. 9, the workpiece is firmly clamped therebetween. On the block 33, inwardly from 'the gripping face 50, is a cam surface 51 which is arranged to engage and lift the jaw 38 slightly, clear of the stock, as the jaws are retracted to open position. A suitable stop pin 52 is provided for limiting the insertion of the stock endwise of the jaws 38. The pin is preferably urged upwardly by a spring 53 so that it can engage the end of the web W of the stock in two different positions of the leg of the J-section illustrated in FIGS. 13 and 14, respectively. The pin 52 may be locked in fixed position by a lock screw 54, when desired, so as to engage the web W.

An important feature of the present invention resides in the fact that the one of the faces 40 or 56 is smooth, while the other face is roughened, knurled, or serrated, .as distinguished from the usual practice in which both faces are rough or serrated. This arrangement provides at least as good a gripping force as that obtained with both gripping faces roughened or serrated. It is of greater advantage to make the face 40 on the movable jaw 38 smooth instead of making the face on the stationary jaw 49 smooth. This provides better and more effective cooperation of the jaw 38 with the stock as the jaw starts sliding along the stock when coming into clamping contact with it. The smooth face slides more readily on the stock and thus does not push the engaged end portion of the stock endwise and cause the stock to bow before it is firmly gripped. The sliding engagement of the smooth face 40 with the stock without appreciably moving the stock endwise is assured'by the resistance to endwise move- .ment imposed on the stock by the serrated surface 59.

that the stock will be well indented by each serration on the surface 59 so that the stock has a large effective area of contact with the jaws. If both surfaces were serrated, the serrations in many instances would have only a line contact with stock at its opposite sides. The fiat surface 46 forces the stock to wrap around, and be dug into by, all of the serrations on the jaw 54 thus giving a very firm gripping action over a large area.

Upon release of the jaws, the stock is held firmly by the rough surface 56 and is instantly released by the smooth surface 4%, so it does not adhere to the latter. Adherence to the surface 4% would cause difficulties in removal of, or impose strains on, the formed piece.

Referring to the stock illustrated in FIGS. 14 and to the jaw 38, the jaw, as mentioned, is provided with a side slot 41. The slot 41 is arranged so that when the web W is gripped between the jaws, the flange P, forming the hook of the J, can be accommodated in the slot 41 while the web is disposed with the flange P facing upwardly. if it is desired to form the metal with a flange facing downwardly, then the jaw is turned upside down and moved to the opposite end of the length of stock. The like gripping head 29 is arranged at the other end of the die and is mounted on the frame 1 in position to clamp the opposite end of the length of stock. Since the gripping heads 29 and 3d are arranged at opposite ends of the length of stock, the head 29 must have its jaws in lefthand relation to the head 3i). The heads are arranged so that the stock can be fed thereinto from the front of the machine. For example, the head 30 has on its side plate 36 a suit-able slot 58 through which the end portion of the stock can be inserted in a direction transversely of its length into a position between the jaws. The head 29 has a corresponding slot 59 for a like purpose. Thus the length of stock can be inserted between the jaws and then gripped thereby for stretch forming. Thereupon, the piston and cylinder assemblage it can be operated for swinging the arm 5 in the proper direction with respect to the side face of the die. The swinging of the arm 5 causes the cam roller 23 to follow along the cam 24, and thus urge the carriage 21, and with it the gripping head 2%, endwise of the stock away from the head 3% thus stretching the stock to the degree required for proper forming, usually above the elastic limit of the stock.

With the stock in stretched condition, it is then worked on by suitable forming tools which reduce its cross section, for example, by suitable punches.

Heretofore, in the stretch forming and punching of sheet metal, the metal was first stretch formed, then released and removed from the stretch forming apparatus, and then placed in a punch press by which holes were punched in the web. The punching occurred after the tension had been relieved.

According to the present invention, the punching is effected while the stock is under tension and held in stretcncxl condition about the die. More accurate results are obtainable by this method. It has been found also that the reduction of cross section of the metal, due to removal of the slugs formed by punching while the metal is under this forming tension, does not cause a further stretching of the metal at the reduced cross sections with resulting distortion of the holes punched.

For the punching operation, suitable punches, indicated generally at 6%, are provided. The details of these punches are best illustrated in FIGS. 10 through 12. As there illustrated, a lower supporting frame 61 is provided with a slideway 61a in which a die button support 62 is mounted. The support 62 carries a die button 63 and has a suitable discharge passage 62:: for discharge of the slugs which are punched out.

The button support 62 is mounted in the support 61 for sliding movement vertically and is moved to fillfifiltifill positions ventically for cooperation with a stationary stripper pad, later to be described, by means of a suitable lineally movable cam 65. The cam 65 is driven by a spring-return piston and cylinder assemblage 66, having a piston 67 with a rod 66 connected to the cam 65. The cam is guided for lineal movement in the support 61a and is in cooperative engagement with complementary cam surfaces 69 on the die support 62. Movement of the cam 65 in the power driven direction, or to the right in FIG. 11, forces the button support 62 upwardly to a maximum position. In this position, it can engage the Web W of the stock when the web is disposed horizontally with the flange F turned downwardly, as in FIG. 14. The supports 61 are provided with suitable slots 7% which afford access to the die 3.

Mounted on the die 3 above the level of the slot 70 is a stripper pad 71 having a central passage 72 aligned with the passage of the die button 62. A punch 73 is carried by a punch holder 74 which is connected to a suitable slide '75. The slide 75 is driven vertically by a reversible piston and cylinder assemblage 76, all in a conventional manner. A combined cover and gauge plate '73 is mounted on the support 61 at the end of the passage 79 in which the cam 65 operates. The passage 79 opens through the forward face of the support 61 in alignment with the combined cover and gauge plate '78.

In the form illustrated, in order for the die button 63 to be in firm engagement with the underside of the web W in the position shown in FIG. 14, the wedge must be moved to its fully extended position in which its free end extends slightly beyond the outer face of the support 61. Accordingly, a cavity 8% is provided for accommodatin the outer end of the cam. On the other hand, if the workpiece is reversed so that it takes the position illustrated in FIG. 13, with the web W disposed horizontally and juxtaposed on the die button 63' and with the flange F disposed upwardly, then the button 63 needs to be raised only an amount equal to the thickness of the decorative covering D. Thus with the decorative covering D lying on the upper surface of the bottom of the slot 70, the undcrface of tie web will be ten thousandth-s thereabove and parallel thereto when engaged by the button.

In order to limit the movement of the cam 65 so that the button 63 is moved only this distance, about .010 of an inch, the combined cover and gauge plate 78 is provided with a projection 81. The cover 78 is bolted to the support 61 so as to be readily removable. When desired to limit the movement of the cam, the cover 78 is merely removed, turned face to face so that the projection 83. is disposed in the passage 79. This projection is such that it limits the movement of the cam 65 to the right, as illustrated in' FIG. 12, and thus limits the movement of the support so that the button 63 is raised just enough above the top surface of the lower wall surface of the slot 7% to engage the underface of the web W while it is horizontal and support the web for punching. The button does not exert any substantial clamping pressure on the stock so as to resist endwise movement of the stock resulting from tension applied by the heads 29 and 3d.

The height of the surface on the carriage 21 which supports the clamping head 29 is different from that on the frame l which supports the head 30. Consequently, the lower heel block 31 and upper block 32 are at different levels relative to the stock being gripped between the jaws. To make right and left hand trim articles, for example for right and left windows, it is only necessary to take the head 36 from the frame, invert it, and move it onto the carriage 21, and to do likewise with the assemblage 29 on the carriage 21, placing it on the frame which originally supported the head 3t With this arrangement, the gripping line on the web of the stock is disposed at the proper elevation so that the flange of the trating at the punched section.

eems it 16. On the other hand, if it is desired to invert the stock, the jaws are inverted as illustrated in FIGURE 17, the serrated jaw being placed above and the smooth jaw below. These cooperate with the stock as shown in FIGURE 18.

Normally, it would be expected that upon the punching operation, the reduction in cross section of the metal in the web at various places would cause the metal to draw out or be strained, due to all of the strain concen- Theoretically, this would distort both the metal and the punched hole. However, such is not the case. The phenomenon by which the stock web and the punched hole retain their shape is not fully understood. It is known that the stock is under tension at the time of punching and is not clamped by the buttons 63. I

Even'thoughthe carriage 21 cannot move any further in the itensioning direction than determined by the cam 24, the tension being resisted by the stock, and which was adequate for stretch forming, does not appear to distort the hole.

While in the illustrated form of the invention, twojawed heads are used, these are chosen because of the cross section of the workpiece, and the principle may be embodied in jaws with a larger number of jaws depending on the cross section to be gripped.

Having thus described my invention, 1 claim:

A stock stretching apparatus for gripping a length of sheet metal stock and applying stretch forming tension thereto in one dimension, and comprising a gripping head including a rigid body having a forward end, means supporting the body for movement forwardly and rearwardly, power operable stretch forming means con-.

nected to the body and operative to urge the body rearwardly to apply stretch forming tension to stock gripped by the head, a pair of gripping jaws having complementary stock gripping surfaces, respectively, the gripping surface of one of said jaws being smooth and the gripping surface of the other of said jaws being rough, supporting means on the body supporting the jaws with the smooth gripping surface below, and facing upwardly toward, the rough gripping surface, and for guided move ment of the jaws relative to each other along predetermined paths, which are fixed relative to the body, in a direction away from each other to a released position and in an opposite direction toward each other to a stock gripping position, said supporting means constraining thev jaws to a position wherein the complementary surfaces are parallel to a common plane and are aligned endwise of said predetermined path with each other, in said stock gripping position, and power operable closure means mounted on the body and operaitively connected to the jaws for moving the jaws relative to each other, independently of the movement of the body by the power operable stretch forming means, along'said predetermined fixedv paths, to gripping position, and operable to apply pressure for holding them in said gripping position sufficiently tightly for stretch forming of the stock by said movement of thebody.

References Qited by the Examiner UNTTED STATES PATENTS 2,101,654 12/37 Sheehan 83-19 2,251,135 7/41 Iknayan et al 83-19 2,460,483 2/49 Berliner 153-2 2,522,319 9/50 Tinley 153-35 2,613,720 10/52 Baker 153-2 2,702,929 3/55 Laddon et al. 24-263 2,866,249 12/58 Normandin 24-263 2,908,316 10/59 Albers 153-35 3,015,353 1/62 Brown 153-32 3,051,217 7/62 Hill et a1 153-35 CHARLES W. LANHAM, Primary Examiner. 

